The present invention relates to a liquid crystal polyester resin composition which has been markedly improved in fluidity, particularly fluidity in molding thin-walled articles, with virtually no deterioration in the mechanical property and heat resistance inherent to liquid crystal polyester.
The technologies in the field of electronics are making a spectacular advance in recent years. In electronic parts such as relay parts, coil bobbins, connectors etc., with the progress toward smaller-sized or thinner-walled products, high levels of performances have come to be required, including high dimensional accuracy, high strength, high rigidity and high solder heat resistance.
Liquid crystal polyester undergoes almost no entanglement between its molecular chains in melting, so that it shows a very low melt viscosity and its molecular chains can be highly oriented in the direction of flow by a small shearing force. Accordingly, molded articles obtained from liquid crystal polyester have high strength and high rigidity though they are highly anisotropic. Further, liquid crystal polyester can provide such thin wall molded articles that have not been obtainable from prior crystalline or amorphous engineering plastics, and can, depending on the structure of the liquid crystal polyester, give articles having a solder heat resistance superior to that of polyphenylene sulfide. For these reasons, liquid crystal polyesters are rapidly coming into wide use as the material for electronic parts.
In the field of electronics, however, with the progress in surface mounting techniques etc. attendant on the trend toward devices of higher integration, increasingly higher level of performances have come to be required for the electronic parts mounted thereon. For example, these parts are required, at a wall thickness of as low as 0.1-0.3 mm, to have mechanical properties including strength and rigidity and heat resistances including solder heat resistance and heat distortion temperature which are equal or superior to those of the products of prior art. The heat resistance and the fluidity in molding thin-walled articles are contradictory to each other, polymers with more excellent fluidity having lower heat resistance. Even in liquid crystal polyesters, few polyesters have been known which can fully meet such requirements for performances.